The studies proposed are intended to accelerate the pace of discovery related to interventions for individuals with cervical spinal cord injury (SCI) who face significant challenges in the performance of everyday activities that require functional use of the hands. Beyond the physical damage to the spinal cord, secondary neuroplastic reorganization in the brain exacerbates functional loss. In some reports, the changes in corticomotor excitability that occur after SCI are similar to those that occur following stroke. By increasing voluntary drive to the hands, function can be improved after SCI. The studies in the parent grant apply to individuals with SCI interventions similar to those gleaned from recent studies of stroke. Newer evidence indicates that high-frequency repetitive transcranial magnetic stimulation (rTMS) may be effective at improving hand function after stroke. The proposed studies will use rTMS with the goal of increasing corticomotor drive to improve hand function in individuals with SCI. These supplemental studies will assess the safety, neurophysiologic effects, and preliminary efficacy of rTMS using a two-week, single-blind, sham-controlled, crossover design in 20 subjects. The following aims will be accomplished: 1) Assess within-session changes in pinch force to quantify the immediate effects of rTMS on force production of the contralateral hand, compared to ipsilateral hand and to sham-rTMS condition, 2) Assess effects of a 3-day course of rTMS to quantify the short-term effects on force production, functional task performance, and cortimotor neurophysiology related to contralateral hand function, compared to ipsilateral hand function and to sham-rTMS, and 3) Assess endurance of effects by quantifying the persistence of effects of rTMS on hand function and force production. These studies expand the aims of the parent grant, support personnel, and invest in technological equipment. The supplement will maximize the information that can be learned about the relationship between corticospinal drive and hand function in individuals with SCI within the 2-year abbreviated funding period. PUBLIC HEALTH RELEVANCE: In individuals with cervical SCI, impairment of hand function severely restricts independence and quality of life by limiting performance of self care, work, and leisure tasks. These studies aim to advance the field of rehabilitation science and reduce the burden of disability by improving hand function in individuals with SCI. Few goals are more important for function, independence, and participation in these individuals.